Autonomous transports for storage and retrieval systems

ABSTRACT

An autonomous transport vehicle for transferring case units to and from predefined storage areas in an automated case unit storage system, the automated case unit storage system including an array of multilevel storage racks with picking aisles passing therebetween and at least one multilevel vertical conveyor having movable shelves, the autonomous transport vehicle including a frame configured to traverse the picking aisles and a transfer deck connecting the picking aisles to the at least one multilevel vertical conveyor for transferring case units between the predefined storage areas and the at least one multilevel vertical conveyor, and a controller connected to the frame, the controller being configured to effect movement of the autonomous transport vehicle through the picking aisles for accessing each storage area within a respective level of the array of multilevel storage racks and each shelf of the at least one multilevel vertical conveyor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/814,937, filed on Jul. 26, 2022, (now U.S. Pat. No. 11,661,279),which is a continuation of U.S. patent application Ser. No. 17/009,399,filed on Sep. 1, 2020, (now U.S. Pat. No. 11,396,427), which is acontinuation of U.S. patent application Ser. No. 16/275,973, filed onFeb. 14, 2019, (now U.S. Pat. No. 10,759,600) which is a continuation ofU.S. patent application Ser. No. 15/137,889, filed on Apr. 25, 2016,(now U.S. Pat. No. 10,207,870) which is a continuation of U.S. patentapplication Ser. No. 13/860,802, filed on Apr. 11, 2013 (now U.S. Pat.No. 9,321,591) which is a continuation of U.S. patent application Ser.No. 12/757,312, filed on Apr. 9, 2010 (now U.S. Pat. No. 8,425,173) andclaims the benefit of U.S. Provisional Patent Application No.61/168,349, filed on Apr. 10, 2009, the disclosures of which areincorporated herein by reference in their entireties.

BACKGROUND 1. Field

The exemplary embodiments generally relate to material handling systemsand, more particularly, to transports for automated storage andretrieval systems.

2. Brief Description of Related Developments

Warehouses for storing case units may generally comprise a series ofstorage racks that are accessible by transport devices such as, forexample, fork lifts, carts and elevators that are movable within aislesbetween or along the storage racks or by other lifting and transportingdevices. These transport devices may be automated or manually driven.Generally the items transported to/from and stored on the storage racksare contained in carriers, for example storage containers such as trays,totes or shipping cases, or on pallets. Generally, incoming pallets tothe warehouse (such as from manufacturers) contain shipping containers(e.g. cases) of the same type of goods. Outgoing pallets leaving thewarehouse, for example, to retailers have increasingly been made of whatmay be referred to as mixed pallets. As may be realized, such mixedpallets are made of shipping containers (e.g. totes or cases such ascartons, etc.) containing different types of goods. For example, onecase on the mixed pallet may hold grocery products (soup can, soda cans,etc.) and another case on the same pallet may hold cosmetic or householdcleaning or electronic products. Indeed some cases may hold differenttypes of products within a single case. Conventional warehousingsystems, including conventional automated warehousing systems do notlend themselves to efficient generation of mixed goods pallets. Inaddition, storing case units in, for example carriers or on palletsgenerally does not allow for the retrieval of individual case unitswithin those carriers or pallets without transporting the carriers orpallets to a workstation for manual or automated removal of theindividual items.

It would be advantageous to have a storage and retrieval system forefficiently storing and retrieving individual case units withoutcontaining those case units in a carrier or on a pallet.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the disclosed embodimentsare explained in the following description, taken in connection with theaccompanying drawings, wherein:

FIG. 1 schematically illustrates an exemplary storage and retrievalsystem in accordance with an exemplary embodiment;

FIGS. 2 and 3A-3C illustrate a transport robot in accordance with anexemplary embodiment;

FIGS. 4A and 4B illustrate partial schematic views of the transportrobot of FIGS. 2, 3A and 3B in accordance with an exemplary embodiment;

FIG. 4C illustrates a schematic view of a transport robot in accordancewith an exemplary embodiment;

FIGS. 5A-5C and 6A-6D illustrate a portion of a transfer arm of thetransport robot of FIGS. 12, 13A and 13B in accordance with an exemplaryembodiment;

FIG. 7 schematically illustrates a control system of the transport robotof FIGS. 2, 3A and 3B in accordance with an exemplary embodiment;

FIGS. 8, 9A and 9B schematically illustrate exemplary operational pathsof a transport robot in accordance with the exemplary embodiments;

FIG. 10 schematically illustrates a portion of the control system ofFIG. 17 in accordance with an exemplary embodiment;

FIGS. 11A-11E, 12A, 12B, 13A and 13B schematically illustrate exemplaryoperational paths of a transport robot in accordance with the exemplaryembodiments;

FIG. 14A illustrates a conventional organization of item storage in astorage bay;

FIG. 14B illustrates an organization of items in a storage bay inaccordance with an exemplary embodiment;

FIG. 14C illustrates a comparison of unused storage space between theitem storage of FIG. 14A and the item storage of FIG. 14B;

FIG. 15 schematically illustrates a conveyor system in accordance withan exemplary embodiment;

FIGS. 16A, 16B, 16C, and 16D illustrate schematic views of a conveyorsystem in accordance with an exemplary embodiment;

FIGS. 17A-17D schematically illustrate a transfer station in accordancewith an exemplary embodiment;

FIGS. 18A and 18B illustrate schematic views of a conveyor system inaccordance with an exemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT(S)

FIG. 1 generally schematically illustrates a storage and retrievalsystem 100 in accordance with an exemplary embodiment. Although theembodiments disclosed will be described with reference to theembodiments shown in the drawings, it should be understood that theembodiments disclosed can be embodied in many alternate forms. Inaddition, any suitable size, shape or type of elements or materialscould be used.

In accordance with one exemplary embodiment the storage and retrievalsystem 100 may operate in a retail distribution center or warehouse to,for example, fulfill orders received from retail stores for case units(where case units as used herein means items not stored in trays, ontotes or on pallets, e.g. uncontained). It is noted that the case unitsmay include cases of items (e.g. case of soup cans, boxes of cereal,etc.) or individual items that are adapted to be taken off of or placedon a pallet. In accordance with the exemplary embodiments, shippingcases or case units (e.g. cartons, barrels, boxes, crates, jugs, or anyother suitable device for holding items) may have variable sizes and maybe used to hold items in shipping and may be configured so they arecapable of being palletized for shipping. It is noted that when, forexample, pallets of items arrive at the storage and retrieval system thecontent of each pallet may be uniform (e.g. each pallet holds apredetermined number of the same item—one pallet holds soup and anotherpallet holds cereal) and as pallets leave the storage and retrievalsystem the pallets may contain any suitable number and combination ofdifferent items (e.g. each pallet may hold different types of items—apallet holds a combination of soup and cereal). In alternate embodimentsthe storage and retrieval system described herein may be applied to anyenvironment in which items are stored and retrieved.

The storage and retrieval system 100 may be configured for installationin, for example, existing warehouse structures or adapted to newwarehouse structures. In one exemplary embodiment, the storage andretrieval system 100 may include in-feed and out-feed transfer stations170, 160, multilevel vertical conveyors 150A, 150B, a storage structure130, and a number of autonomous vehicular transport robots 110 (referredto herein as “bots”). In alternate embodiments the storage and retrievalsystem may also include robot or bot transfer stations (as described in,for example, U.S. patent application Ser. No. 12/757,220, entitled“STORAGE AND RETRIEVAL SYSTEM,” with Attorney Docket Number1127P013867-US (PAR) previously incorporated by reference herein) thatmay provide an indirect interface between the bots and the multilevelvertical conveyor 150A, 150B. The in-feed transfer stations 170 andout-feed transfer stations 160 may operate together with theirrespective multilevel vertical conveyors 150A, 150B for transferringitems to and from one or more levels of the storage structure 130. Themultilevel vertical conveyors may be substantially similar to thosedescribed in U.S. patent application Ser. No. 12/757,354, entitled “LIFTINTERFACE FOR STORAGE AND RETRIEVAL SYSTEMS,” with Attorney DocketNumber 1127P013868-US (PAR), previously incorporated by reference hereinin its entirety. It is noted that while the multilevel verticalconveyors are described herein as being dedicated inbound conveyors 150Aand outbound conveyors 150B, in alternate embodiments each of theconveyors 150A, 150B may be used for both inbound and outbound transferof case units/items from the storage and retrieval system. The bots 110may be configured to place items, such as the above described retailmerchandise, into picking stock in the one or more levels of the storagestructure 130 and then selectively retrieve ordered items for shippingthe ordered items to, for example, a store or other suitable location.In one exemplary embodiment, the bots 110 may interface directly withthe multilevel vertical conveyors 150A, 150B through, for example,access provided by transfer areas 295 (FIGS. 8 and 11A-11E) while inother exemplary embodiments, the bots 110 may interface indirectly withthe respective multilevel vertical conveyors 150A, 150B in any suitablemanner such as through bot transfer stations.

The storage structure 130 may be substantially similar to the storagestructure described in U.S. patent application Ser. No. 12/757,381,entitled “STORAGE AND RETRIEVAL SYSTEM,” with Attorney Docket Number1127P013678-US (PAR) and U.S. patent application Ser. No. 12/757,220,entitled “STORAGE AND RETRIEVAL SYSTEM,” with Attorney Docket Number1127P013867-US (PAR), previously incorporated herein by reference intheir entirety. For example, the storage structure 130 may includemultiple levels of storage rack modules, where each level includespicking aisles 130A (FIGS. 8-9D) that provide access to the storageracks, transfer decks 130B (FIGS. 8-9D) that provide access to thepicking aisles, and charging stations (not shown) that are configured toreplenish, for example, a battery pack of the bots 110. The bots 110 andother suitable features of the storage and retrieval system 100 may becontrolled by, for example, one or more central system control computers(e.g. control server) 120 through, for example, any suitable network180. In one example, the central control computer and network may besubstantially similar to those described in U.S. patent application Ser.No. 12/757,354, entitled “LIFT INTERFACE FOR STORAGE AND RETRIEVALSYSTEMS,” having Attorney Docket Number 1127P013868-US (PAR), U.S.patent application Ser. No. 12/757,381, entitled “STORAGE AND RETRIEVALSYSTEM,” having Attorney Docket Number 1127P013678-US (PAR); U.S. patentapplication Ser. No. 12/757,220, entitled “STORAGE AND RETRIEVALSYSTEM,” with Attorney Docket Number 1127P013867-US (PAR); and U.S.patent application Ser. No. 12/757,337, entitled “CONTROL SYSTEM FORSTORAGE AND RETRIEVAL SYSTEMS,” with Attorney Docket Number1127P013888-US (PAR), previously incorporated by reference herein intheir entirety. The network 180 may be a wired network, a wirelessnetwork or a combination of a wireless and wired network using anysuitable type and/or number of communication protocols. It is notedthat, in one exemplary embodiment, the system control server 120 may beconfigured to manage and coordinate the overall operation of the storageand retrieval system 100 and interface with, for example, a warehousemanagement system, which in turn manages the warehouse facility as awhole.

As an exemplary operation of an order fulfillment process of the storageand retrieval system 100, case units for replenishing the picking stockare input at, for example, depalletizing workstations so that case unitsbundled together on pallets (or other suitable container-like transportsupports) are separated and individually carried on, for example,conveyors or other suitable transfer mechanisms (e.g. manned orautomated carts, etc.) to the in-feed transfer stations 170. The in-feedtransfer stations 170 assembles the case units into pickfaces (e.g. oneor more case units that may form a bot load) and loads the pickfacesonto respective multilevel vertical conveyors 150A, which carry thepickfaces to a predetermined level of the storage structure 130. Bots110 located on the predetermined level of the storage structure 130interface with the multilevel vertical conveyor 150A at, for example,the transfer areas 295 for removing the pickfaces from the multilevelvertical conveyor 150A. The bots 110 transfer the pickfaces from themultilevel vertical conveyors 150A to a predetermined storage module ofthe storage structure 130. When an order for individual case units ismade the bots 110 retrieve the corresponding pickfaces from a designatedstorage module of the storage structure 130 and transfer the orderedcase units to transfer areas 295 located on a level of the storagestructure 130 from which the ordered case units were picked. The bots110 interfaces with multilevel vertical conveyor 150B for transferringthe pickfaces to the multilevel vertical conveyor 150B. The multilevelvertical conveyor 150B transports the ordered case unit(s) of thepickface to the out-feed transfer stations 160 where the individual caseunits are transported to palletizing workstations by conveyors 230 wherethe individual case units are placed on outbound pallets (or othersuitable container-like transport supports) for shipping to a customer.

As may be realized, the storage and retrieval system 100 may includemultiple in-feed and out-feed multilevel vertical conveyors 150A, 150Bthat are accessible by, for example, bots 110 on each level of thestorage and retrieval system 100 so that one or more case unit(s),uncontained or without containment (e.g. case unit(s) are not sealed intrays), can be transferred from a multilevel vertical conveyor 150A,150B to each storage space on a respective level and from each storagespace to any one of the multilevel vertical conveyors 150A, 150B on arespective level. The bots 110 may be configured to transfer theuncontained case units between the storage spaces and the multilevelvertical conveyors with one pick (e.g. substantially directly betweenthe storage spaces and the multilevel vertical conveyors). By way offurther example, the designated bot 110 picks the uncontained caseunit(s) from a shelf 730 of a multilevel vertical conveyor, transportsthe uncontained case unit(s) to a predetermined storage area of thestorage structure 130 and places the uncontained case unit(s) in thepredetermined storage area (and vice versa). In one exemplaryembodiment, the storage and retrieval system 100 may include a botpositioning system for positioning the bot adjacent the shelves 730 ofthe multilevel vertical conveyor 150A, 150B for picking/placing adesired pickface from a predetermined one of the shelves 730 (e.g. thebot 110 is positioned so as to be aligned with the pickface on the shelfor a position on the shelf designated to receive the pickface). The botpositioning system may also be configured to correlate the extension ofthe bot transfer arm 1235 with the movement (e.g. speed and location) ofthe shelves 730 so that the transfer arm 1235 is extended and retractedto remove (or place) pickfaces from predetermined shelves 730 of themultilevel vertical conveyors 150A, 150B. It is noted that at least aportion of the bot positioning system may reside within the controlsystem 1220 (FIG. 7 ) of the bot 110.

Referring now to FIGS. 2-6D, the bots 110 that transfer loads (e.g.pickfaces formed of at least one case unit) between, for example, themultilevel vertical conveyors 150A, 150B and the storage shelves of arespective level of storage structure 130 will be described. It is notedthat in one exemplary embodiment the bots 110 may transfer loadsdirectly to and/or from the multilevel vertical conveyors 150A, 150B aswill be described below, while in alternate embodiments the bots 110 mayinterface with the multilevel vertical conveyors indirectly such asthrough the bot transfer stations. In one example, the bots 110 may beconfigured for substantially continuous operation. For exemplarypurposes only, the bots 110 may have a duty cycle of about ninety-five(95) percent. In alternate embodiments the bots may have any suitableduty cycle and operational periods.

As can be seen in FIG. 2 , the bots 110 generally include a frame 1200,a drive system 1210, a control system 1220, and a payload area 1230. Thedrive system 1210 and control system 1220 may be mounted to the frame inany suitable manner. The frame may form the payload area 1230 and beconfigured for movably mounting a transfer arm or effector 1235 to thebot 110.

In one exemplary embodiment, the drive system 1210 may include two drivewheels 1211, 1212 disposed at a drive end 1298 of the bot 110 and twoidler wheels 1213, 1214 disposed at a driven end 1299 of the bot 110.The wheels 1211-1214 may be mounted to the frame 1200 in any suitablemanner and be constructed of any suitable material, such as for example,low-rolling-resistance polyurethane. In alternate embodiments the bot110 may have any suitable number of drive and idler wheels. In oneexemplary embodiment, the wheels 1211-1214 may be substantially fixedrelative to the a longitudinal axis 1470 (FIG. 4B) of the bot 110 (e.g.the rotational plane of the wheels is fixed in a substantially parallelorientation relative to the longitudinal axis 1470 of the bot) to allowthe bot 110 to move in substantially straight lines such as when, forexample, the bot is travelling on a transfer deck 130B (e.g. FIGS. 8-9B)or within a picking isle 130A (e.g. FIGS. 8-9B). In alternateembodiments, the rotational plane of one or more of the drive wheels andidler wheels may be pivotal (e.g. steerable) relative to thelongitudinal axis 1470 of the bot for providing steering capabilities tothe bot 110 by turning the rotational planes of one or more of the idleror drive wheels relative to the longitudinal axis 1470. The wheels1211-1214 may be substantially rigidly mounted to the frame 1200 suchthat the axis of rotation of each wheel is substantially stationaryrelative to the frame 1200. In alternate embodiments the wheels1211-1214 may be movably mounted to the frame by, for example, anysuitable suspension device, such that the axis of rotation of the wheels1211-1214 is movable relative to the frame 1200. Movably mounting thewheels 1211-1214 to the frame 1200 may allow the bot 110 tosubstantially level itself on uneven surfaces while keeping the wheels1211-1214 in contact with the surface.

Each of the drive wheels 1211, 1212 may be individually driven by arespective motor 1211M, 1212M. The drive motors 1211M, 1212M may be anysuitable motors such as, for exemplary purposes only, direct currentelectric motors. The motors 1211M, 1212M may be powered by any suitablepower source such as by, for example, a capacitor 1400 (FIG. 4B) mountedto the frame 1200. In alternate embodiments the power source may be anysuitable power source such as, for example, a battery or fuel cell. Instill other alternate embodiments the motors may be alternating currentelectric motors or internal combustion motors. In yet another alternateembodiment, the motors may be a single motor with dual independentlyoperable drive trains/transmissions for independently driving each drivewheel. The drive motors 1211M, 1212M may be configured forbi-directional operation and may be individually operable under, forexample, control of the control system 1220 for effecting steering ofthe bot 110 as will be described below. The motors 1211M, 1212M may beconfigured for driving the bot 110 at any suitable speed with anysuitable acceleration when the bot is in either a forward orientation(e.g. drive end 1298 trailing the direction of travel) or a reverseorientation (e.g. drive end 1298 leading the direction of travel). Inthis exemplary embodiment, the motors 1211M, 1212M are configured fordirect driving of their respective drive wheel 1211, 1212. In alternateembodiments, the motors 1211M, 1212M may be indirectly coupled to theirrespective wheels 1211, 1212 through any suitable transmission such as,for example, a drive shaft, belts and pulleys and/or a gearbox. Thedrive system 1210 of the bot 110 may include an electrical brakingsystem such as for example, a regenerative braking system (e.g. tocharge, for example, a capacitor 1400 (FIG. 4B) powering the bot 110under braking). In alternate embodiments, the bot 110 may include anysuitable mechanical braking system. The drive motors may be configuredto provide any suitable acceleration/deceleration rates and any suitablebot travel speeds. For exemplary purposes only the motors 1211M, 1212Mmay be configured to provide the bot (while the bot is loaded at fullcapacity) a rate of acceleration/deceleration of about 3.048 m/sec², atransfer deck 130B cornering speed of about 1.524 m/sec and a transferdeck straightaway speed of about 9.144 m/sec or about 10 m/sec.

As noted above drive wheels 1211, 1212 and idler wheels 1213, 1214 aresubstantially fixed relative to the frame 1200 for guiding the bot 110along substantially straight paths while the bot is travelling on, forexample, the transfer decks 130B (e.g. FIGS. 8-9B). Corrections in thestraight line paths may be made through differential rotation of thedrive wheels 1211, 1212 as described herein. In alternate embodiments,guide rollers 1250, 1251 may be mounted to the frame to aid in guidingthe bot 110 on the transfer deck 130B such as through contact with awall 1801, 2100 (FIG. 8 ) of the transfer deck 130B. However, in thisexemplary embodiment the fixed drive and idler wheels 1211-1214 may notprovide agile steering of the bot 110 such as when, for example, the bot110 is transitioning between the picking aisles 130A, transfer decks130B or transfer areas 295 (FIGS. 8 and 11A-11E). In one exemplaryembodiment, the bot 110 may be provided with one or more retractablecasters 1260, 1261 for allowing the bot 110 to make, for example,substantially right angle turns when transitioning between the pickingaisles 130A, transfer decks 130B and bot transfer stations 140A, 140B.It is noted that while two casters 1260, 1261 are shown and described,in alternate embodiments the bot 110 may have more or less than tworetractable casters. The retractable casters 1260, 1261 may be mountedto the frame 1200 in any suitable manner such that when the casters1260, 1261 are in a retracted position both the idler wheels 1213, 1214and drive wheels 1211, 1212 are in contact with a flooring surface suchas surface 1300S of the rails 1300 or a transfer deck 130B of thestorage structure 130, whereas when the casters 1260, 1261 are loweredthe idler wheels 1213, 1214 are lifted off the flooring surface. As thecasters 1260, 1261 are extended or lowered the idler wheels 1213, 1214are lifted off of the flooring surface so that the driven end 1299 ofthe bot 110 can be pivoted about a point P (FIG. 14B) of the botthrough, for example, differential rotation of the drive wheels 1211,1212. For example, the motors 1211M, 1212M may be individually anddifferentially operated for causing the bot 110 to pivot about point Pwhich is located, for example, midway between the wheels 1211, 1212while the driven end 1299 of the bot swings about point P accordinglyvia the casters 1260, 1261.

In other exemplary embodiments, the idler wheels 1213, 1214 may bereplaced by non-retractable casters 1260′, 1261′ (FIG. 4C) where thestraight line motion of the bot 110 is controlled by differingrotational speeds of each of the drive wheels 1211, 1212 as describedherein. The non-retractable casters 1260′, 1261′ may be releasablylockable casters such that the casters 1260′, 1261′ may be selectivelylocked in predetermined rotational orientations to, for example, assistin guiding the bot 110 along a travel path. For example, during straightline motion of the bot 110 on the transfer deck 130B and/or within thepicking aisles 130A the non-retractable casters 1260′, 1261′ may belocked in an orientation such that the wheels of the casters 1260′,1261′ are substantially in-line with a respective one of the drivewheels 1213, 1214 (e.g. the rotational plane of the wheels of thecasters is fixed in a substantially parallel orientation relative to thelongitudinal axis 1470 of the bot). The rotational plane of the wheelsof non-retractable casters 1260′, 1261′ may be locked and releasedrelative to the longitudinal axis 1470 of the bot 110 in any suitablemanner. For example, a controller 1701 (FIG. 7 ) of the bot 110 may beconfigured to effect the locking and releasing of the casters 1260′,1261′ by for example controlling any suitable actuator and/or lockingmechanism. In alternate embodiments any other suitable controllerdisposed on or remotely from the bot 110 may be configured to effect thelocking and releasing of the casters 1260′, 1261′.

The bot 110 may also be provided with guide wheels 1250-1253. As can bebest seen in FIGS. 3B and 3C, while the bot 110 is travelling in, forexample, the picking aisles 130A and/or transfer areas 295 (FIGS. 8 and11A-11E) the movement of the bot 110 may be guided by a tracked or railguidance system. It is noted that the transfer areas 295 may allow thebots 110 to access transport shelves 730 of the multilevel verticalconveyors 150A, 150B. The rail guidance system may include rails 1300disposed on either side of the bot 110. The rails 1300 and guide wheels1250-1253 may allow for high-speed travel of the bot 110 without complexsteering and navigation control subsystems. The rails 1300 may beconfigured with a recessed portion 1300R shaped to receive the guidewheels 1250-1253 of the bot 110. In alternate embodiments the rails mayhave any suitable configuration such as, for example, without recessedportion 1300R. The rails 1300 may be integrally formed with or otherwisefixed to, for example, one or more of the horizontal and verticalsupports 398, 399 of the storage rack structure 130. As can be seen inFIG. 3C the picking aisles may be substantially floor-less such that botwheel supports 1300S of the guide rails 1300 extend away from thestorage areas a predetermined distance to allow a sufficient surfacearea for the wheels 1211-1214 (or in the case of lockable casters,wheels 1260′, 1261′) of the bot 110 to ride along the rails 1300. Inalternate embodiments the picking aisles may have any suitable floorthat extends between adjacent storage areas on either side of thepicking aisle. In one exemplary embodiment, the rails 1300 may include afriction member 1300F for providing traction to the drive wheels 1211,1212 of the bot 110. The friction member 1300F may be any suitablemember such as for example, a coating, an adhesive backed strip or anyother suitable member that substantially creates a friction surface forinteracting with the wheels of the bot 110.

While four guide wheels 1250-1253 are shown and described it should beunderstood that in alternate embodiments the bot 110 may have anysuitable number of guide wheels. The guide wheels 1250-1253 may bemounted to, for example, the frame 1200 of the bot in any suitablemanner. In one exemplary embodiment, the guide wheels 1250-1253 may bemounted to the frame 1200, through for example, spring and damperdevices so as to provide relative movement between the guide wheels1250-1253 and the frame 1200. The relative movement between the guidewheels 1250-1253 and the frame may be a dampening movement configuredto, for example, cushion the bot 110 and its payload against any changein direction or irregularities (e.g. misaligned joints between tracksegments, etc.) in the track 1300. In alternate embodiments, the guidewheels 1250-1253 may be rigidly mounted to the frame 1200. The fitmentbetween the guide wheels 1250-1253 and the recessed portion 1300R of thetrack 1300 may be configured to provide stability (e.g. anti-tipping) tothe bot during, for example, cornering and/or extension of the transferarm 1235 (e.g. to counteract any tipping moments created by acantilevered load on the transfer arm). In alternate embodiments the botmay be stabilized in any suitable manner during cornering and/orextension of the transfer arm 1235. For example, the bot 110 may includea suitable counterweight system for counteracting any moment that iscreated on the bot through the extension of the transfer arm 1235.

The transfer arm 1235 may be movably mounted to the frame 1200 within,for example, the payload area 1230. It is noted that the payload area1230 and transfer arm 1235 may be suitably sized for transporting casesin the storage and retrieval system 100. For example, the width W of thepayload area 1230 and transfer arm 1235 may be substantially the same asor larger than a depth D (FIG. 6B) of the storage shelves 600. Inanother example, the length L of the payload area 1230 and transfer arm1235 may be substantially the same as or larger than the largest itemlength transferred through the system 100 with the item length beingoriented along the longitudinal axis 1470 (FIG. 4B) of the bot 110.

Referring also to FIGS. 4A and 4B, in this exemplary embodiment thetransfer arm 1235 may include an array of fingers 1235A, one or morepusher bars 1235B and a fence 1235F. In alternate embodiments thetransfer arm may have any suitable configuration and/or components. Thetransfer arm 1235 may be configured to extend and retract from thepayload area 1230 for transferring loads to and from the bot 110. In oneexemplary embodiment, the transfer arm 1235 may be configured to operateor extend in a unilateral manner relative to the longitudinal axis 1470of the bot (e.g. extend from one side of the bot in direction 1471) forincreasing, for example, reliability of the bot while decreasing thebots complexity and cost. It is noted that where the transfer arm 1235is operable only to one side of the bot 110, the bot may be configuredto orient itself for entering the picking aisles 130A and/or transferareas 295 with either the drive end 1298 or the driven end 1299 facingthe direction of travel so that the operable side of the bot is facingthe desired location for depositing or picking a load. In alternateembodiments the bot 110 may be configured such that the transfer arm1235 is operable or extendable in a bilateral manner relative to thelongitudinal axis 1470 of the bot (e.g. extendable from both sides ofthe bot in directions 1471 and 1472).

In one exemplary embodiment, the fingers 1235A of the transfer arm 1235may be configured such that the fingers 1235A are extendable andretractable individually or in one or more groups. For example, eachfinger may include a locking mechanism 1410 that selectively engageseach finger 1235A to, for example, the frame 1200 of the bot 110 or amovable member of the transfer arm 1235 such as the pusher bar 1235B.The pusher bar 1235B (and any fingers coupled to the pusher bar), forexample, may be driven by any suitable drive such as extension motor1495. The extension motor 1495 may be connected to, for example, thepusher bar, through any suitable transmission such as, for exemplarypurposes only, a belt and pulley system 1495B (FIG. 4A).

In one exemplary embodiment, the locking mechanism for coupling thefingers 1235A to, for example, the pusher bar 1235B may be, for example,a cam shaft driven by motor 1490 that is configured to causeengagement/disengagement of each finger with either the pusher bar orframe. In alternate embodiments, the locking mechanism may includeindividual devices, such as solenoid latches associated withcorresponding ones of the fingers 1235A. It is noted that the pusher barmay include a drive for moving the pusher bar in the direction of arrows1471, 1472 for effecting, for example, a change in orientation (e.g.alignment) of a load being carried by the bot 110, gripping a load beingcarried by the bot 110 or for any other suitable purpose. In oneexemplary embodiment, when one or more locking mechanisms 1410 areengaged with, for example, the pusher bar 1235B the respective fingers1235A extend and retract in the direction of arrows 1471, 1472substantially in unison with movement of the pusher bar 1235B while thefingers 1235A whose locking mechanisms 1410 are engaged with, forexample, the frame 1200 remain substantially stationary relative to theframe 1200.

In another exemplary embodiment, the transfer arm 1235 may include adrive bar 1235D or other suitable drive member. The drive bar 1235D maybe configured so that it does not directly contact a load carried on thebot 110. The drive bar 1235D may be driven by a suitable drive so thatthe drive bar 1235D travels in the direction of arrows 1471, 1472 in amanner substantially similar to that described above with respect to thepusher bar 1235B. In this exemplary embodiment, the locking mechanisms1410 may be configured to latch on to the drive bar 1235D so that therespective fingers 1235A may be extended and retracted independent ofthe pusher bar and vice versa. In alternate embodiments the pusher bar1235B may include a locking mechanism substantially similar to lockingmechanism 1410 for selectively locking the pusher bar to either thedrive bar 1235D or the frame 1200 where the drive bar is configured tocause movement of the pusher bar 1235B when the pusher bar 1235B isengaged with the drive bar 1235D.

In one exemplary embodiment, the pusher bar 1235B may be a one-piece barthat spans across all of the fingers 1235A. In other exemplaryembodiments, the pusher bar 1235B may be a segmented bar having anysuitable number of segments 1235B1, 1235B2. Each segment 1235B1, 1235B2may correspond to the groups of one or more fingers 1235A such that onlythe portion of the pusher bar 1235B corresponding to the finger(s) 1235Athat are to be extended/retracted is moved in the direction of arrows1471, 1472 while the remaining segments of the pusher bar 1235B remainstationary so as to avoid movement of a load located on the stationaryfingers 1235A.

The fingers 1235A of the transfer arm 1235 may be spaced apart from eachother by a predetermined distance so that the fingers 1235A areconfigured to pass through or between corresponding support legs 620L1,620L2 of the storage shelves 600 (FIG. 5A) and corresponding supportfingers 910 of the shelves 730 on the multilevel vertical conveyors150A, 150B. In alternate embodiments the fingers 1235A may be configuredto pass through corresponding support fingers of bot transfer stationsfor passing the bot load to multilevel vertical conveyor through the bottransfer station. The spacing between the fingers 1235A and a length ofthe fingers of the transfer arm 1235 allows an entire length and widthof the loads being transferred to and from the bot 110 to be supportedby the transfer arm 1235.

The transfer arm 1235 may include any suitable lifting device(s) 1235Lconfigured to move the transfer arm 1235 in a direction 1350 (FIG. 13B)substantially perpendicular to a plane of extension/retraction of thetransfer arm 1235.

Referring also to FIGS. 5A-5C, in one example, a load (substantiallysimilar to loads 750-753) is acquired from, for example, a storage shelf600 by extending the fingers 1235A of the transfer arm 1235 into thespaces 620S between support legs 620L1, 620L2 of the storage shelf 600and under one or more target items 1500 located on the shelf 600. Thetransfer arm lift device 1235L is suitably configured to lift thetransfer arm 1235 for lifting the one or more target items 1500 off ofthe shelf 600. The fingers 1235A are retracted so that the one or moretarget items are disposed over the payload area 1230 of the bot 110. Thelift device 1235L lowers the transfer arm 1235 so the one or more targetitems are lowered into the payload area 1230 of the bot 110. Inalternate embodiments, the storage shelves 600 may be configured with alift motor for raising and lowering the target items where the transferarm 1235 of the bot 110 does not include a lift device 1235L. FIG. 5Billustrates an extension of three of the fingers 1235A for transferringa load 1501. FIG. 5C shows a shelf 1550 having two items or loads 1502,1503 located side by side. In FIG. 5C, three fingers 1235A of thetransfer arm 1235 are extended for acquiring only load 1502 from theshelf 1550. As can be seen in FIG. 5C, it is noted that the loadscarried by the bots 110 may include cases of individual items (e.g. load1502 includes two separate boxes and load 1503 includes three separateboxes). It is also noted that in one exemplary embodiment the extensionof the transfer arm 1235 may be controlled for retrieving apredetermined number of items from an array of items. For example, thefingers 1235A in FIG. 5C may be extended so that only item 1502A isretrieved while item 1502B remains on the shelf 1550. In anotherexample, the fingers 1235A may be extended only part way into a shelf600 (e.g. an amount less than the depth D of the shelf 600) so that afirst item located at, for example, the front of the shelf (e.g.adjacent the picking aisle) is picked while a second item located at theback of the shelf, behind the first item, remains on the shelf.

As noted above the bot 110 may include a retractable fence 1235F.Referring to FIGS. 6A-6D, the fence 1235F may be movably mounted to theframe 1200 of the bot 110 in any suitable manner so that the loads, suchas load 1600, pass over the retracted fence 1235F as the loads aretransferred to and from the bot payload area 1230 as can be seen in FIG.6A. Once the load 1600 is located in the payload area 1230, the fence1235F may be raised or extended by any suitable drive motor 1610 so thatthe fence 1235F extends above the fingers 1235A of the bot 110 forsubstantially preventing the load 1600 from moving out of the payloadarea 1230 as can be seen in FIG. 6B. The bot 110 may be configured togrip the load 1600 to, for example, secure the load during transport.For example, the pusher bar 1235B may move in the direction of arrow1620 towards the fence 1235F such that the load 1600 is sandwiched orgripped between the pusher bar 1235B and the fence 1235F as can be seenin FIGS. 6C and 6D. As may be realized, the bot 110 may include suitablesensors for detecting a pressure exerted on the load 1600 by the pusherbar 1235B and/or fence 1235F so as to prevent damaging the load 1600. Inalternate embodiments, the load 1600 may be gripped by the bot 110 inany suitable manner.

Referring again to FIGS. 4B and 4C, the bot 110 may include a roller bed1235RB disposed in the payload area 1230. The roller bed 1235RB mayinclude one or more rollers 1235R disposed transversely to thelongitudinal axis 1470 of the bot 110. The rollers 1235R may be disposedwithin the payload area 1230 such that the rollers 1235R and the fingers1235A are alternately located so that the fingers 1235A may pass betweenthe rollers 1235R for transferring items to and from the payload area1230 as described above. One or more pushers 1235P may be disposed inthe payload area 1230 such that a contact member of the one or morepushers 1235P extends and retracts in a direction substantiallyperpendicular to the axis of rotation of the rollers 1235R. The one ormore pushers 1235P may be configured to push the load 1600 back andforth within the payload area 1230 in the direction of arrow 1266 (e.g.substantially parallel to the longitudinal axis 1470 of the bot 110)along the rollers 1235R for adjusting a position of the load 1600longitudinally within the payload area 1230. In alternate embodiments,the rollers 1235R may be driven rollers such that a controller of, forexample, the bot drives the rollers for moving the load 1600 such thatthe load is positioned at a predetermined location within the payloadarea 1230. In still other alternate embodiments the load may be moved tothe predetermined location within the payload area in any suitablemanner. The longitudinal adjustment of the load 1600 within the payloadarea 1230 may allow for positioning of the loads 1600 for transferringthe loads from the payload area to, for example, a storage location orother suitable location such as the multilevel vertical conveyors 150A,150B or bot transfer stations 140A, 140B.

Referring now to FIG. 7 , the control system 1220 of the bot will bedescribed. The control system 1220 may be configured to providecommunications, supervisory control, bot localization, bot navigationand motion control, case sensing, case transfer and bot powermanagement. In alternate embodiments the control system 1220 may beconfigured to provide any suitable services to the bot 110. The controlsystem 1220 may include any suitable programs or firmware configured forperforming the bot operations described herein. The control system 1220may be configured to allow for remote (e.g. over a network) debugging ofthe bot. In one example, the firmware of the bot may support a firmwareversion number that can be communicated over, for example, the network180 so the firmware may be suitably updated. The control system 1220 mayallow for assigning a unique bot identification number to a respectivebot 110 where the identification number is communicated over the network180 (FIG. 1 ) to, for example, track a status, position or any othersuitable information pertaining to the bot 110. In one example, the botidentification number may be stored in a location of the control system1220 such that the bot identification number is persistent across apower failure but is also changeable.

In one exemplary embodiment, the control system 1220 may be divided intoa front end 1220F (FIG. 2 ) and back end 1220B (FIG. 2 ) having anysuitable subsystems 1702, 1705. The control system 1220 may include anon-board computer 1701 having, for example, a processor, volatile andnon-volatile memory, communication ports and hardware interface portsfor communicating with the on-board control subsystems 1702, 1705. Thesubsystems may include a motion control subsystem 1705 and aninput/output subsystem 1702. In alternate embodiments, the bot controlsystem 1220 may include any suitable number of portions/subsystems.

The front end 1220F may be configured for any suitable communications(e.g. synchronous or asynchronous communications regarding bot commands,status reports, etc.) with the control server 120. The communicationsbetween the bot 110 and the control server 120 may, in one exemplaryembodiment, provide for a substantially automatic bootstrap from, forexample, initial installation of the bot 110, operational failure of thebot 110 and/or bot replacement. For example, when a bot 110 isinitialized, the bot may obtain an identification number and subscribeto a bot proxy 2680 (FIG. 26A) via communication with the front end1220F. This allows the bot to become available for receiving tasks. Thefront end 1220F may receive and decompose tasks assigned to the bot 110and reduce the task into primitives (e.g. individual commands) that theback end 1220B can understand. In one example, the front end 1220F mayconsult any suitable resources such as, for example, a map of thestorage structure 130 (FIG. 1 ) to decompose a task into the primitivesand to determine the various movement related parameters (e.g. velocity,acceleration, deceleration, etc.) for each portion of the task. Thefront end 1220F may pass the primitives and movement related parametersto the back end 1220B for execution by the bot 110. The bot front end1220F may be configured as a pair of state machines where a first one ofthe state machines handles communication between the front end 1220F andthe control server 120 and a second one of the state machines handlescommunication between the front end 1220F and the back end 1220B. Inalternate embodiments the front end 1220F may have any suitableconfiguration. The first and second state machines may interact witheach other by generating events for each other. The state machines mayinclude a timer for handling timeouts such as during, transfer deck 130Baccess. In one example, when a bot 110 is entering a transfer deck 130B(e.g. FIG. 8 ), a bot proxy of the central system control computers mayinform the front end 1220F of a predetermined entrance time that the botis to enter the transfer deck 130B. The front end 1220F may start thetimer of the state machines according to a time the bot is to wait(based on the predetermined entrance time) before entering the deck. Itis noted that the timers (e.g. clocks) of the state machines and the botproxy 2680 may be synchronized clocks so as to substantially avoidcollisions between bots travelling on the transfer deck 130B and botsentering the transfer deck 130B.

The back end 1220B may be configured to effect the functions of the botdescribed above (e.g. lowering the casters, extending the fingers,driving the motors, etc.) based on, for example, the primitives receivedfrom the front end 1220F. In one example, the back end 122B may monitorand update bot parameters including, but not limited to, bot positionand velocity and send those parameters to the bot front end 1220F. Thefront end 1220F may use the parameters (and/or any other suitableinformation) to track the bot's 110 movements and determine the progressof the bot task(s). The front end 1220F may send updates to, forexample, the bot proxy 2680 so that the control server 120 can track thebot movements and task progress and/or any other suitable botactivities.

The motion control subsystem 1705 may be part of the back end 1220B andconfigured to effect operation of, for example, the drive motors 1211M,1212M, 1235L, 1495, 1490, 1610 of the bot 110 as described herein. Themotion control subsystem 1705 may be operatively connected to thecomputer 1701 for receiving control instructions for the operation of,for example, servo drives (or any other suitable motor controller)resident in the motion control subsystem 1705 and subsequently theirrespective drive motors 1211M, 1212M, 1235L, 1495, 1490, 1610. Themotion control subsystem 1705 may also include suitable feedbackdevices, such as for example, encoders, for gathering informationpertaining to the drive motor operation for monitoring, for example,movement the transfer arm 1235 and its components (e.g. when the fingers1235A are latched to the pusher bar, a location of the pusher bar,extension of the fence, etc.) or the bot 110 itself. For example, anencoder for the drive motors 1211M, 1212M may provide wheel odometryinformation, and encoders for lift motor 1235L and extension motor 1495may provide information pertaining to a height of the transfer arm 1235and a distance of extension of the fingers 1235A. The motion controlsubsystem 1705 may be configured to communicate the drive motorinformation to the computer 1701 for any suitable purpose including butnot limited to adjusting a power level provided to a motor.

The input/output subsystem 1702 may also be part of the back end 1220Band configured to provide an interface between the computer 1701 and oneor more sensors 1710-1716 of the bot 110. The sensors may be configuredto provide the bot with, for example, awareness of its environment andexternal objects, as well as the monitor and control of internalsubsystems. For example, the sensors may provide guidance information,payload information or any other suitable information for use inoperation of the bot 110. For exemplary purposes only, the sensors mayinclude a bar code scanner 1710, slat sensors 1711, line sensors 1712,case overhang sensors 1713, arm proximity sensors 1714, laser sensors1715 and ultrasonic sensors 1716.

The bar code scanner(s) 1710 may be mounted on the bot 110 in anysuitable location. The bar code scanners(s) 1710 may be configured toprovide an absolute location of the bot 110 within the storage structure130. The bar code scanner(s) 1710 may be configured to verify aislereferences and locations on the transfer decks by, for example, readingbar codes located on, for example the transfer decks, picking aisles andtransfer station floors to verify a location of the bot 110. The barcode scanner(s) 1710 may also be configured to read bar codes located onitems stored in the shelves 600.

The slat sensors 1711 may be mounted to the bot 110 at any suitablelocation. The slat sensors 1711 may be configured to count the slats orlegs 620L1, 620L2 of the storage shelves 600 (e.g. FIG. 5A) fordetermining a location of the bot 110 with respect to the shelving of,for example, the picking aisles 130A. The slat information may be usedby the computer 1701 to, for example, correct the bot's odometry andallow the bot 110 to stop with its fingers 1235A positioned forinsertion into the spaces between the legs 620L1, 620L2. In oneexemplary embodiment, the bot may include slat sensors 1711 on the driveend 1298 and the driven end 1299 of the bot to allow for slat countingregardless of which end of the bot is facing the direction the bot istravelling. The slat sensors 1711 may be any suitable sensors such as,for example, close range triangulation or “background suppression”sensors. The slat sensors 1711 may be oriented on the bot 110 so thatthe sensors see down into the slats and ignore, for example, the thinedges of the legs 620L1, 620L2. For exemplary purposes only, in oneexemplary embodiment the slat sensors 1711 may be mounted at about a 15degree angle from perpendicular (relative to the longitudinal axis 1470(FIG. 4B) of the bot 110). In alternate embodiments the slat sensors1711 may be mounted on the bot in any suitable manner.

The line sensors 1712 may be any suitable sensors mounted to the bot inany suitable location, such as for exemplary purposes only, on bumpers1273 (FIG. 2 ) disposed on the drive and driven ends of the bot 110. Forexemplary purposes only, the line sensors may be diffuse infraredsensors. The line sensors 1712 may be configured to detect guidancelines provided on, for example, the floor of the transfer decks 130B(e.g. FIG. 8 ). The bot 110 may be configured to follow the guidancelines when travelling on the transfer decks 130B and defining ends ofturns when the bot is transitioning on or off the transfer decks 130B.The line sensors 1712 may also allow the bot 110 to detect indexreferences for determining absolute localization where the indexreferences are generated by crossed guidance lines. In this exemplaryembodiment the bot 110 may have about six line sensors 1712 but inalternate embodiments the bot 110 may have any suitable number of linesensors.

The case overhang sensors 1713 may be any suitable sensors that arepositioned on the bot to span the payload area 1230 adjacent the topsurface of the fingers 1235A. The case overhang sensors 1713 may bedisposed at the edge of the payload area 1230 to detect any loads thatare at least partially extending outside of the payload area 1230. Inone exemplary embodiment, the case overhang sensors 1713 may provide asignal to the computer 1701 (when there is no load or other itemsobstructing the sensor) indicating that the fence 1235F may be raisedfor securing the load(s) within the payload area 1230. In otherexemplary embodiments, the case overhang sensors 1713 may also confirm aretraction of the fence 1235F before, for example, the fingers 1235A areextended and/or a height of the transfer arm 1235 is changed.

The arm proximity sensors 1714 may be mounted to the bot 110 in anysuitable location, such as for example, on the transfer arm 1235. Thearm proximity sensors 1714 may be configured to sense objects around thetransfer arm 1235 and/or fingers 1235A of the transfer arm 1235 as thetransfer arm 1235 is raised/lowered and/or as the fingers 1235A areextended/retracted. Sensing objects around the transfer arm 1235 may,for exemplary purposes only, substantially prevent collisions betweenthe transfer arm 1235 and objects located on, for example, shelves 600(e.g. FIG. 5A) or the horizontal and/or vertical supports of the storagestructure 130.

The laser sensors 1715 and ultrasonic sensors 1716 (collectivelyreferred to as case sensors) may be configured to allow the bot 110 tolocate itself relative to each case unit forming the load carried by thebot 110 before the case units are picked from, for example, the storageshelves 600 and/or multilevel vertical conveyor (or any other locationsuitable for retrieving payload). The case sensors may also allow thebot to locate itself relative to empty storage locations for placingcase units in those empty storage locations. This location of the botrelative to the case units to be picked and/or empty storage locationsfor placing the case units may be referred to as bot localization, whichwill be described in greater detail below. The case sensors may alsoallow the bot 110 to confirm that a storage slot (or other loaddepositing location) is empty before the payload carried by the bot isdeposited in, for example, the storage slot. In one example, the lasersensor 1715 may be mounted to the bot at a suitable location fordetecting edges of items to be transferred to (or from) the bot 110. Thelaser sensor 1715 may work in conjunction with, for example,retro-reflective tape (or other suitable reflective surface, coating ormaterial) located at, for example, the back of the shelves 600 to enablethe sensor to “see” all the way to the back of the storage shelves 600.The reflective tape located at the back of the storage shelves allowsthe laser sensor 1715 to be substantially unaffected by the color,reflectiveness, roundness or other suitable characteristics of the itemslocated on the shelves 600. The ultrasonic sensor 1716 may be configuredto measure a distance from the bot 110 to the first item in apredetermined storage area of the shelves 600 to allow the bot 110 todetermine the picking depth (e.g. the distance the fingers 1235A travelinto the shelves 600 for picking the item(s) off of the shelves 600).One or more of the case sensors may allow for detection of caseorientation (e.g. skewing of cases within the storage shelves 600) by,for example, measuring the distance between the bot 110 and a frontsurface of the case units to be picked as the bot 110 comes to a stopadjacent the case units to be picked. The case sensors may allowverification of placement of a case unit on, for example, a storageshelf 600 by, for example, scanning the case unit after it is placed onthe shelf.

It is noted that the computer 1701 and its subsystems 1702, 1705 may beconnected to a power bus for obtaining power from, for example, thecapacitor 1400 through any suitable power supply controller 1706. It isnoted that the computer 1701 may be configured to monitor the voltage ofthe capacitor 1400 to determine its state of charge (e.g. its energycontent). In one exemplary embodiment, the capacitor may be chargedthrough charging stations located at, for example, one or more transferareas 295 (FIGS. 8 and 11A-11E) or at any other suitable location of thestorage structure 130 so that the bot is recharged when transferringpayloads and remains in substantially continuous use. The chargingstations may be configured to charge the capacitor 1400 within the timeit takes to transfer the payload of the bot 110. For exemplary purposesonly, charging of the capacitor 1400 may take about 15 seconds. Inalternate embodiments, charging the capacitor may take more or less thanabout 15 seconds. During charging of the capacitor 1400 the voltagemeasurement may be used by the computer 1701 to determine when thecapacitor is full and to terminate the charging process. The computer1701 may be configured to monitor a temperature of the capacitor 1400for detecting fault conditions of the capacitor 1400.

The computer 1701 may also be connected to a safety module 1707 whichincludes, for example, an emergency stop device 1311 (FIG. 3A) whichwhen activated effects a disconnection of power to, for example, themotion control subsystem 1705 (or any other suitable subsystem(s) of thebot) for immobilizing or otherwise disabling the bot 110. It is notedthat the computer 1701 may remain powered during and after activation ofthe emergency stop device 1311. The safety module 1707 may also beconfigured to monitor the servo drives of the motion control subsystem1705 such that when a loss of communication between the computer and oneor more of the servo drives is detected, the safety module 1707 causesthe bot to be immobilized in any suitable manner. For example, upondetection of a loss of communication between the computer 1701 and oneor more servo drives the safety module 1707 may set the velocity of thedrive motors 1211M, 1212M to zero for stopping movement of the bot 110.

The communication ports of the control system 1220 may be configured forany suitable communications devices such as, for example, a wirelessradio frequency communication device 1703 (including one or moreantennae 1310) and any suitable optical communication device 1704 suchas, for example, an infrared communication device. The wireless radiofrequency communication device 1703 may be configured to allowcommunication between the bot 110 and, for example, the control server120 and/or other different bots 110 over any suitable wireless protocol.For exemplary purposes only, the wireless protocol for communicatingwith the control server 120 may be the wireless 802.11 network protocol(or any other suitable wireless protocol). Communications within the botcontrol system 1220 may be through any suitable communication bus suchas, for example, a control network area bus. It is noted that thecontrol server 120 and the bot control system 1220 may be configured toanticipate momentary network communication disruptions. For example, thebot may be configured to maintain operation as long as, for example, thebot 110 can communicate with the control server 120 when the bot 110transits a predetermined track segment and/or other suitable way point.The optical communication device 1704 may be configured to communicatewith, for example, the bot transfer stations for allowing initiation andtermination of charging the capacitor 1400. The bot 110 may beconfigured to communicate with other bots 110 in the storage andretrieval system 100 to form a peer-to-peer collision avoidance systemso that bots can travel throughout the storage and retrieval system 100at predetermined distances from each other in a manner substantiallysimilar to that described in U.S. patent application Ser. No.12/757,337, entitled “CONTROL SYSTEM FOR STORAGE AND RETRIEVAL SYSTEMS,”with Attorney Docket Number 1127P013888-US (PAR), previouslyincorporated by reference herein in its entirety.

Referring to FIGS. 2, 4B and 8-13B, bot navigation and motion controlwill be described. Generally, in accordance with the exemplaryembodiments, the bot 110 has, for example, three modes of travel. Inalternate embodiments the bot 110 may have more than three modes oftravel. For exemplary purposes only, in the picking aisles 130A the bottravels on wheels 1211-1214 (or lockable casters 1260′, 1261′ in lieu ofidler wheels 1213, 1214) and is guided by guide wheels 1250-1253 againstthe sides of track 1300 (FIG. 3B). On the transfer deck 130B, the bot110 uses casters 1261, 1262 (or releases lockable casters 1260′, 1261′)while making substantially right angle turns when transitioning from/tothe picking aisles 130A or transfer stations 140A, 140B. For travelinglong distances on, for example, the transfer deck 130B the bot 110travels on wheels 1211-1214 (or lockable casters 1260′, 1261′ in lieu ofidler wheels 1213, 1214 where the casters 1260′, 1261′ are rotationallylocked as described above) using a “skid steering” algorithm (e.g.slowing down or stopping rotation of one drive wheel relative to theother drive wheel to induce a turning motion on the bot) to followguidance lines 1813-1817 on the transfer deck 130B.

When traveling in the picking aisles 130A, the bot 110 travels insubstantially straight lines. These substantially straight line moveswithin the picking aisles 130A can be in either direction 1860, 1861 andwith either bot orientation (e.g. a forward orientation with the driveend 1298 trailing the direction of travel and a reverse orientation withthe drive end 1298 leading the direction of travel). During straightline motion on the transfer deck 130B the bot 110 travels in, forexemplary purposes only, a counterclockwise direction 1863, with aforward bot orientation. In alternate embodiments the bot may travel inany suitable direction with any suitable bot orientation. In still otheralternate embodiments, there may be multiple travel lanes allowing botsto travel in multiple directions (e.g. one travel lane has a clockwisedirection of travel and another travel lane has a counter-clockwisedirection of travel). In one example, the turns to and from the pickingaisles 130A and/or transfer areas 295 are about 90 degrees where thecenter point of rotation P of the bot is located substantially midwaybetween the drive wheels 1211, 1212 such that the bot can rotateclockwise or counterclockwise. In alternate embodiments the bot turnsmay be more or less than about 90 degrees. In another example, the botmay make a substantially 180 degree turn (i.e. two substantially 90degree turns made in sequence without a stop) as will be describedbelow.

As described above, the transfer deck 130B may include guidance lines1810-1817 for guiding the bot 110. The guidance lines 1810-1817 may beany suitable lines adhered to, formed in or otherwise affixed to thetransfer deck 130B. For exemplary purposes only, in one example theguidance lines may be a tape affixed to the surface of the transfer deck130B. In this exemplary embodiment the transfer deck 130B includes atrack 1800 having a first side 1800A and a second side 1800B separatedby a wall 1801. The first and second sides 1800A, 1800B of the track1800 are joined by end track sections 1800E (only one of which is shownin FIG. 8 ). In alternate embodiments the track 1800 may have anysuitable configuration. Each of the first and second sides 1800A, 1800Bincludes two travel lanes defined by, for example, guidance lines 1813,1814 and 1816, 1817 respectively. The end track portions 1800E include,for example, one travel lane defined by, for example, guidance line1815. In alternate embodiments the sections/sides of the track 1800 mayhave any suitable number of travel lanes defined in any suitable manner.In accordance with the exemplary embodiments each picking lane 130Aand/or transfer area 295, includes a lead in/out guidance line1810-1812. The lead in/out guidance lines 1810-1812 and the singleguidance line 1815 of the end track portions 1800E may be detected bythe bot 110 as index marks for bot localization during longline-following moves. The lead in/out guidance lines 1810-1812 andguidance line 1815 may also be detected by the bot 110 as referencemarks for making turns.

When the bot 110 moves in substantially straight lines, such as in thepicking aisles 130A and/or transfer areas 295, the drives for motors1211M, 1212M may be configured as torque controllers. For example, thecomputer 1701 may be configured to close a velocity loop as shown inFIG. 10 using the average of the velocity feedback from both wheels1211, 1212 as the “bot velocity”. To improve performance and avoidvelocity loop instabilities, the velocity loop may be augmented withtorque-feedforward and operated at a low gain. The computer 1701 mayalso be configured to close a position loop as also shown in FIG. 10 forfinal position at a stop location of the bot 110. The computer 1701 mayalso be configured to sum in a differential torque offset to implementline following. It is noted that the drive wheels 1211, 1212 may loosetraction with the transfer deck 130A or floor of a picking aisle 130A ortransfer area 295 when the flooring surfaces and/or the wheels arecontaminated with liquids, dirt or other particulates. The velocitycontrol loop may be configured to mitigate the loss of traction bybacking off the torque to both wheels 1211, 1212 whenever feedbackprovided by, for example, an encoder for one or both wheels 1211, 1212indicates a velocity higher than a predetermined velocity of the bot110.

When travelling long distances on, for example, the transfer deck, thebot 110 travels on drive wheels 1211, 1212 and idler wheels 1213, 1214(or locked casters 1260′, 1261′) so that the bot is deterred fromveering off of the straight line trajectory through the fixed nature ofthe drive wheels 1211, 1212 and idler wheels 1213, 1214 (or lockedcasters 1260′, 1261′). The computer 1701 may be configured with anysuitable line following algorithm to substantially ensure that the bot110 maintains travel in a straight line. The line following algorithmmay also allow for correction of initial line following errors due to,for example, misalignment from turns. In one exemplary embodiment thebot 110 uses line sensors 1712 to estimate its heading and offset from aguidance line 1810-1817. The bot 110 may be configured to use, forexample, any suitable algorithm such as a fuzzy logic algorithm togenerate corrections in the travel path of the bot 110. The correctionmay be applied as a differential torque to the wheels as the bot istravelling (e.g. skid steering—rotating one drive wheel slower than theother drive wheel to produce increased drag on one side of the bot forinducing a turning moment on the bot).

For turns, such as for example, substantially right angle turns, thedrives for motors 1211M, 1212M may be configured as positioncontrollers. For example the drives may be commanded by the computer1701 to rotate their respective wheels in opposite directions for apredetermined distance to generate a pivot turn of slightly more thanabout 90 degrees. When for example, line sensors 1712 detect a stoppingguidance line, the turning move is terminated. In alternate embodimentsthe drives for the motors 1211M, 1212M may be operated in any suitablemanner for driving the bot in substantially straight lines or duringturns.

FIGS. 9A and 9B illustrate an exemplary turn sequence for asubstantially 90 degree turn made by the bot 110 while transitioningonto the transfer deck 130B from a picking aisle 130A. In this example,the bot is traveling in a forward orientation in the direction of arrow1910. As the bot 110 exits the picking aisle 130A, the bot 110 lowersthe casters 1260, 1261 (FIG. 4A) so that the idler wheels 1213, 1214 arelifted off of the transfer deck 130B (or unlocks casters 1260′, 1261′).Using line sensors 1712 located at for example the driven end 1299 ofthe bot 110, the bot 110 detects the inner travel lane guidance line1814 and then using corrected wheel odometry, stops with its pivot pointP at or close to the outer travel lane guidance line 1813. The bot 110rotates about 90 degrees in the direction of arrow 1920 using adifferential torque in the drive motors 1211M, 1212M to turn the drivewheels 1211, 1212 in opposite directions such that the bot 110 rotatesabout point P. The bot 110 detects the guidance line 1813 with the linesensors 1712 and terminates the turn. The bot 110 raises the casters1260, 1260 so that the idler wheels 1213, 1214 contact the transfer deck130B (or locks casters 1260′, 1261′) and proceeds to follow guidanceline 1813 using, for example, line following. It is noted that turningof the bot to enter, for example, picking aisle 130A may occur insubstantially the same manner as that described above for exiting thepicking aisle 130A.

FIGS. 11A-13B illustrate exemplary travel paths of a bot 110 includingstraight line travel and turn sequences. It is noted that while thespecific examples of bot travel are shown and described, the bot 110 maybe configured to perform any suitable number of turns and transitionbetween any suitable number of travel lanes in any suitable manner fortravelling throughout a respective level of the storage structure 130.FIG. 11A illustrates a travel path of the bot 110 where the bot 110transitions from one, for example, picking aisle (or transfer station),across the transfer deck 130B and into a transfer area 295 (or otherpicking aisle) with the bot 110 transitioning from a reverse orientation(e.g. drive end 1298 leading) to a forward orientation (e.g. drive end1298 trailing). In this example, the bot 110 exits the picking aisle130A in a reverse orientation such that a line sensor(s) 1712 disposedsubstantially at pivot point P detects the inner travel lane guidanceline 1814. The bot 110 pivots about point P in a counterclockwisedirection in a manner substantially similar to that described above withrespect to FIGS. 9A and 9B. The bot follows guidance line 1814 in aforward orientation until, for example, line sensors 1712 (locatedproximately to or at one or more of the drive end 1298 and driven end1299 of the bot 110) detect the crossing of guidance lines 1814 and 1815(FIG. 8 ) at which point the bot 110 pivots counterclockwise about pointP in a manner similar to that described above so that the bot followsline 1815 substantially to a point where guidance line 1815 crosses theinner travel lane guidance line 1816. At the crossing of guidance lines1815, 1816 the bot 110 pivots counterclockwise to follow guidance line1816. The bot follows guidance line 1816 until the line sensors 1712detect a crossing of guidance lines 1816 and 1812 at which point the botpivots clockwise to enter transfer area 295 in a forward orientation.

FIG. 11B illustrates an exemplary travel path of the bot 110 where thebot exits the picking aisle 130A in a reverse orientation and enterstransfer area 295 in a reverse orientation. In this example, the motionof the bot is substantially similar to that described above with respectto FIG. 11A, however, after travelling around wall 1801 the bottransitions to the outer travel lane guidance line 1817 so that the bot110 is in a reverse orientation. The reverse orientation of the bot 110allows the bot to pivot counterclockwise into an open area of thetransfer deck 130B for entering the transfer area 295 in a forwardorientation without colliding with the outside wall 2100 of the transferdeck 130B.

FIG. 11C illustrates the bot 110 exiting the picking aisle 130A in aforward orientation and entering transfer area 295 in a forwardorientation. The motion of the bot is substantially similar to thatdescribed above however, in this example, the bot 110 transitions fromouter travel lane guidance line 1813 to inner travel lane guidance line1816 so that the bot can enter the transfer area 295 in a forwardorientation.

FIGS. 11D and 11E illustrate the bot 110 exiting the picking aisle 130Ain a forward orientation and entering the transfer area 295 in a reverseorientation using the outer travel lane guidance lines 1813 and 1817.The motion of the bot 110 may be substantially similar to that describedabove, however as the bot 110 travels along guidance line 1815 the bot110 makes three turns 2110-2112 (e.g. where turns 2110, 2111 turn thebot substantially 180 degrees along guidance line 1815) to orient thebot 110 for making the final turn 2113 into the transfer area 295. Ascan be seen in FIG. 11E, without the additional turn the bot 110 wouldnot be able to transition from outer travel lane guidance line 1813 ontoouter travel lane guidance line 1817 without colliding with the outerwall 2100 (as indicated by the shaded area) using line following asdescribed herein.

FIGS. 12A and 12B illustrate an exemplary travel path of bot 110 frompicking aisle 130A1 to picking aisle 130A2 where travel of the bot 110within the picking aisle 130A1 is in a forward orientation and travelwithin picking aisle 130A2 is in a reverse orientation. In this example,the bot uses the outer travel lane guidance line 1813 for transitioningbetween picking aisles 130A1, 130A2. As can be seen in FIG. 12A whentravelling along the outer travel lane guidance line 1813 and enteringpicking aisle 130A2 the bot pivots in a direction so the driven end 1299of the bot swings towards the inner travel lane of the transfer deck130B so as to avoid colliding with the outer wall 2100 as shown in FIG.12B.

FIGS. 13A and 13B illustrate an exemplary travel path of bot 110 frompicking aisle 130A1 to picking aisle 130A2 where travel of the bot 110within the picking aisles 130A1, 130A2 is in a reverse orientation. Inthis example, the bot uses the inner travel lane guidance line 1814 fortransitioning between picking aisles 130A1, 130A2. As can be seen inFIG. 13A when travelling along the inner travel lane guidance line 1814the bot pivots in a direction so the driven end 1299 of the bot swingstowards the outer travel lane of the transfer deck 130B so as to avoidcolliding with the inner wall 1801 as shown in FIG. 13B.

It is noted that the bot may be configured to transition between thetracked travel lanes of the picking aisles 130A and the open transferdeck 130B in any suitable manner. In one exemplary embodiment, theguidance lines 1810-1812 may guide the bot into the tracks 1300 of thepicking aisles. In alternate embodiments, one or more of the sensors1710-1716 may allow the bot 110 to detect, for example, edges or othersuitable features of the tracks 1300 (FIG. 3B) and position itself sothe bot 110 passes between opposing tracks 1300 with the guide wheelscontacting the recesses 1300R in the tracks 1300.

In accordance with one exemplary embodiment, in the above describedexamples of the bot travel paths, when the bot is turning the bot issupported by the drive wheels 1211, 1212 and the casters 1260, 1261 (orcasters 1260′, 1261′). The straight line moves of the bot may be madewith the bot supported on the drive wheels 1211, 1212 and the idlerwheels 1213, 1214 (or casters 1260′, 1261′). As noted above, anycorrections to the bot travel path while the bot is traveling in astraight line may be made using skid steering. In alternate embodiments,the bot may travel in a straight line path with the casters 1260, 1261deployed. In still other alternate embodiments, correction to the botsstraight line travel paths may be made through steerable wheels.

Referring again to FIG. 7 , the bot 110 can determine its positionwithin the storage and retrieval system 100 for transitioning throughthe storage structure 130 as described above through, for example, botlocalization. In one exemplary embodiment bot localization may bederived through one or more of bot odometrey, slat counting, indexcounting and bar code reading. As described above, the bot odometry maybe provided from encoders associated with, for example, wheels 1211-1214(FIG. 2 ). It is noted that encoder information from each wheel1211-1214 may be averaged and scaled in any suitable manner to provide adistance traveled by the bot. In alternate embodiments, the distancetraveled by the bot may be obtained from the wheel encoder informationin any suitable manner. The slat counting may be provided by, forexample, the slat sensors 1711 as the bot travels through the pickingaisles. The slat counting may supplement the odometry information whenthe bot is within the picking aisles. The index counting may beprovided, by for example, the line sensors 1712 as the bot passes overcrossed sections of the guidance lines 1810-1817 (FIG. 8 ). The indexcounting may supplement the bot odometry when the bot is traveling onthe transfer deck 130B. Bar code reading may be provided by bar codescanner 1710. The bar code reading may be configured to allow the bot110 to determine an initial position of the bot such as when the bot ispowered up from an off or dormant state. The bar codes may be located attransfer stations 140A, 140B (FIG. 1 ) or any other suitable locationwithin the storage structure 130 for initializing the bot 110. Bar codesmay also be located within the picking aisles and on the transfer deckto, for example, confirm bot location and correct for missed slats orindexes. The on-board computer 1701 of the bot 110 may be configured touse any suitable combination of bot odometrey, slat counting, indexcounting and bar code reading to determine the bot's 110 position withinthe storage structure 130. In alternate embodiments, the computer 1701may be configured to determine the location of the bot using only one orany suitable combination of bot odometrey, slat counting, index countingand bar code reading. In still other alternate embodiments, the locationof the bot may be determined in any suitable manner such as through, forexample, an indoor spatial positioning system. The indoor spatialpositioning system may be substantially similar to a global positioningsystem and use any suitable technique for determining the position of anobject such as, for example, acoustic, optical, or radio frequencysignaling.

In one exemplary embodiment, one or more of the sensors 1710-1716described above may allow for dynamic positioning of bots 110 within thepicking aisles 130A in any suitable manner. The position at which thebot 110 is stopped for dynamically allocating case units may bedetermined by, for example, the control server 120 (FIG. 1 ), thecontrol system 1220 of the bot or by a combination thereof. For example,dynamic allocation of the storage space may be determined by, forexample, the control server 120 in any suitable manner such that anyopen storage spaces in the storage structure 130 are filled with itemshaving a size capable of fitting within those open storage spaces. Thecontrol server may communicate to the appropriate components of thestorage and retrieval system 100, for example, a location of apredetermined storage location and an appropriately sized case unit orcase units for placement in the predetermined storage location. Thatcase unit may be transferred into the storage and retrieval system 100where a bot 110 delivers the case unit to the predetermined storagelocation. As a non-limiting example, the sensors 1710-1716 of the bots110 may count slats 620L1, 620L2 (FIG. 5A) and/or detect edges of caseunits on the storage shelves for dynamically positioning the bots forplacing the case unit in the predetermined storage location. Dynamicallypositioning the bots 110 and/or the dynamic allocation of shelf storagespace may allow for the positioning of case units having varying lengthsin each storage bay 5000, 5001 (FIGS. 14A and 14B) such that the use ofthe storage space is maximized. For example, FIG. 14A illustrates astorage bay 5000 divided into storage slots S1-S4 as is done inconventional storage systems. The size of the storage slots S1-S4 may bea fixed size dependent on a size of the largest case unit (e.g. caseunit 5011) to be stored on the shelf 600 of the storage bay 5000. As canbe seen in FIG. 14A, when case units 5010, 5012, 5013 of varyingdimensions, which are smaller than case unit 5011, are placed in arespective storage slot S1, S2, S4 a significant portion of the storagebay capacity, as indicated by the shaded boxes, remains unused. Inaccordance with an exemplary embodiment, FIG. 14B illustrates a storagebay 5001 having dimensions substantially similar to storage bay 5000. InFIG. 14B the case units 5010-5016 are placed on the shelf 600 usingdynamic allocation. As can be seen in FIG. 14B, dynamically allocatingthe storage space allows placement of case units 5014-5016 on shelf 600in addition to case units 5010-5013 (which are the same case unitsplaced in storage bay 5000 described above) such that the unused storagespace, as indicated by the hatched boxes, is less than the unusedstorage space using the fixed slots of FIG. 14A. FIG. 14C illustrates aside by side comparison of the unused storage space for the fixed slotsand dynamic allocation storage described above. It is noted that theunused storage space of bay 5001 using dynamic allocation may bedecreased even further by decreasing the amount of space between thecase units 5010-5016 which may allow for placement of additional caseunits on the shelf 600. As may be realized, as items are placed withinthe storage structure the open storage spaces may be analyzed, by forexample the control server 120, after each case unit placement anddynamically re-allocated according to a changed size of the open storagespace so that additional case units having a size corresponding to (orless than) a size of the re-allocated storage space may be placed in there-allocated storage space.

Referring now to FIG. 15 , the multilevel vertical conveyors, such asconveyor 150A are supplied with uncontained case units 1000 from in-feedtransfer stations 170 (FIG. 1 ). As described above, the in-feedtransfer stations 170 may include one or more of depalletizingworkstations, conveyors 240, conveyor interfaces/bot load accumulators1010A, 1010B and conveyor mechanisms 1030. As can be seen in FIG. 15 ,uncontained case units 1000 are moved from, for example depalletizingworkstations by conveyors 240. In this example, each of the positionsA-D is supplied by a respective in-feed transfer station. As may berealized, while the transfer of case units is being described withrespect to shelves 730′ it should be understood that transfer of caseunits to shelves 730 occurs in substantially the same manner. Forexample, position A may be supplied by in-feed transfer station 170A andposition C may be supplied by in-feed transfer station 170B. Referringalso to FIG. 16A the in-feed transfer stations 170A, 170B, for supplyingsimilar sides of the shelf 730 (in this example positions A and C, whichare disposed side by side, form a first side 1050 of the shelf 730 andpositions B and D, which are disposed side by side, form a second side1051 of the shelf 730), may be located one above the other in ahorizontally staggered stacked arrangement (an exemplary stackedarrangement is shown in FIG. 16A). In other exemplary embodiments, thestacked arrangement may be configured so that the in-feed transferstations are disposed vertically in-line one above the other and extendinto the multilevel vertical conveyors by different amounts forsupplying, for example, positions A and B or positions C and D wherepositions A and B (and positions C and D) are disposed one in front ofthe other, rather than side by side. In alternate embodiments, thein-feed transfer stations may have any suitable configuration andpositional arrangement. As can be seen in FIG. 15 , the first side 1050and second side 1051 of the shelf 730 are loaded (and unloaded) inopposing directions such that each multilevel vertical conveyor 150A islocated between respective transfer areas 295A, 295B where the firstside 1050 interfaces with a transfer area 295B and the second side 1051interfaces with transfer area 295A.

In this exemplary embodiment, the accumulators 1010A, 1010B areconfigured to form the uncontained case units 1000 into the individualpick faces 750-753 prior to loading a respective position A-D on themultilevel vertical conveyor 730. In one exemplary embodiment, thecomputer workstation 700 and/or control server 120 may provideinstructions or suitably control the accumulators 1010A, 1010B (and/orother components of the in-feed transfer stations 170) for accumulatinga predetermined number of items to form the pickfaces 750-753. Theaccumulators 1010A, 1010B may align the case units in any suitablemanner (e.g. making one or more sides of the items flush, etc.) and, forexample, abut the items together. The accumulators 1010A, 1010B may beconfigured to transfer the pickfaces 750-753 to respective conveyormechanisms 1030 for transferring the pickfaces 750-753 to a respectiveshelf position A-D. In one exemplary embodiment the conveyor mechanisms1030 may include belts or other suitable feed devices for moving thepickfaces 750-753 onto transfer platforms 1060. The transfer platforms1060 may include spaced apart fingers for supporting the pickfaces750-753 where the fingers 910 of the shelves 730 are configured to passbetween the fingers of the transfer platforms 1060 for lifting (orplacing) the pickfaces 750-753 from the transfer platforms 1060. Inanother exemplary embodiment, the fingers of the transfer platforms 1060may be movable and serve to insert the pickfaces 750-753 into the pathof the shelves 730 in a manner similar to that described below withrespect to the bot transfer stations 140. In alternate embodiments thein-feed transfer stations 170 (and out-feed transfer stations 160) maybe configured in any suitable manner for transferring case units (e.g.the pickfaces formed by the case units) onto or from respectivemultilevel vertical conveyors 150A, 150B.

It is noted that while the interface between the bot transfer stations140 and the multilevel vertical conveyors 150A, 150B are described itshould be understood that interfacing between the bots 110 and themultilevel vertical conveyors 150A, 150B occurs in a substantiallysimilar manner (e.g. as described in U.S. patent application Ser. No.12/757,312, Attorney Docket Number 1127P013869-US (PAR), entitled“AUTONOMOUS TRANSPORTS FOR STORAGE AND RETRIEVAL SYSTEMS,” previouslyincorporated by reference herein in its entirety). For exemplarypurposes only, referring now to FIGS. 16B and 17A-17D, the multilevelvertical conveyors 150A transfer pickfaces 750, 752 from, for example,the in-feed transfer stations 170 (or any other suitable device orloading system) to, for example, the bot transfer stations 140associated with each of the levels in the storage structure 130. Inother examples, the pickfaces 750, 752 may be transferred directly fromthe multilevel vertical conveyors 150A to the bots 110 as describedbelow. As may be realized, the bot transfer stations 140 are disposed onrespective levels of the storage structure adjacent the path of travelof the shelves 730 of a respective multilevel vertical conveyor 150A. Inone exemplary embodiment, there may be a bot transfer station 140corresponding to each of the positions A and C on the shelves 730 (andpositions A-D with respect to shelf 730′). For example, a first bottransfer station 140 may remove load 750 from position A on shelf 730while another bot transfer station 140 may remove pickface 752 fromposition C on shelf 730 and so on. In other exemplary embodiments, onebot transfer station 140 may serve to remove or place case units in morethan one position A, C on the shelves 730. For example, one bot transferstation 140 may be configured for removing pickfaces 750, 752 from oneor more of positions A, C of shelf 730. In alternate embodiments,referring also to FIG. 15 , one bot transfer station 140 may beconfigured for removing pickfaces 750, 752 from one or more of positionsA, C on a first side 1050 of the shelf 730′ while another bot transferstation 140 may be configured to remove pickfaces 751, 753 from one ormore positions B, D on a second side 1051 of the shelf 730′. Inalternate embodiments the bot transfer stations 140 may have anysuitable configuration for accessing any suitable number of positionsA-D of the shelves 730, 730′.

Each bot transfer station 140 may include a frame 1100, one or moredrive motors 1110 and a carriage system 1130. The frame 1100 may haveany suitable configuration for coupling the bot transfer station 140 to,for example, any suitable supporting feature of the storage structure130, such as a horizontal or vertical support. The carriage system 1130may be movably mounted to the frame 1100 through, for example, rails1120 that are configured to allow the carriage system 1130 to movebetween retracted and extended positions as shown in FIGS. 17A and 17B.The carriage system 1130 may include a carriage base 1132 and fingers1135. The fingers 1135 may be mounted to the carriage base 1132 in aspaced apart arrangement so that the fingers 1135 extend from thecarriage base 1132 in a cantilevered fashion. It is noted that eachfinger 1135 may be removably mounted to the carriage base 1132 forfacilitating replacement or repair of individual fingers 1135. Inalternate embodiments the fingers and carriage base may be of unitaryone-piece construction. The fingers 1135 of the bot transfer stations140 may be configured to pass between the fingers 910 (FIG. 16B) of theshelves 730 of the multilevel vertical conveyors 150A (FIG. 1 ) forremoving pickfaces such as pickfaces 1150 (which may be substantiallysimilar to pickfaces 750-753) from the shelves 730. The bot transferstation 140 may also include a load positioning device 1140 thatretractably extends between, for example, the spaced apart fingers 1135in the direction of arrow 1181 for effecting positioning of thepickfaces 1150 in a predetermined orientation relative to the bottransfer station 140. In still other alternate embodiments the carriagesystem 1130 may have any suitable configuration and/or components. Theone or more drive motors 1110 may be any suitable motors mounted to theframe 1100 for causing the extension/retraction of the carriage system1130 and the extension/retraction of the positioning device 1140 in anysuitable manner such as by, for exemplary purposes only, drive belts orchains. In alternate embodiments, the carriage system and positioningdevice may be extended and retracted in any suitable manner.

In operation, referring also to FIGS. 16C, 16D, 18A and 18B, inboundpickfaces (e.g. pickfaces, which include one or more case units, thatare being transferred into the storage and retrieval system) such aspickface 1150 are loaded on and will circulate around the multilevelvertical conveyor 150A and be removed from a respective conveyor by, forexample, one or more bots 110 for placement in a storage area of thestorage structure. As will be described further below, in the exemplaryembodiments the input loading sequencing of case units onto themultilevel vertical conveyors 150A, 150B (e.g. such as at correspondingfeeder input sides of transfer stations 170 and bot transfer locationson respective storage levels) may be substantially independent from theoutput or unloading sequence of the multilevel vertical conveyors 150A,150B (e.g. such as at corresponding output sides of transfer stations160 and bot transfer locations on respective storage levels) and viceversa. In one example, the pickface 1150 may be loaded onto the shelves730 during an upward travel of the multilevel vertical conveyor 150A andoff loaded from the shelves 730 during downward travel of the multilevelvertical conveyor 150A. By way of example, multilevel vertical conveyorshelves 730 i and 730 ii (FIG. 16D) may be loaded sequentially, but whenunloaded, shelf 730 ii may be unloaded before shelf 730 i. It is notedthat the shelves 730 may be loaded through one or more cycles of themultilevel vertical conveyor. In alternate embodiments the pickfaces maybe loaded or off loaded from the shelves 730 in any suitable manner. Asmay be realized, the position of the case units on the multilevelvertical conveyor shelf 730 defines the pickface position that the bot110 picks from. The bot may be configured to pick any suitable load orpickface from the shelf 730 regardless of the pickface position on theshelf 730 or the size of the pickface. In one exemplary embodiment, thestorage and retrieval system 100 may include a bot positioning systemfor positioning the bot adjacent the shelves 730 for picking a desiredpickface from a predetermined one of the shelves 730 (e.g. the bot 110is positioned so as to be aligned with the pickface). The botpositioning system may also be configured to correlate the extension ofa bot transfer arm with the movement (e.g. speed and location) of theshelves 730 so that the transfer arm is extended and retracted to remove(or place) pickfaces from predetermined shelves 730 of the multilevelvertical conveyors 150A, 150B. For exemplary purposes only, the bot 110may be instructed by, for example, the computer workstation 700 orcontrol server 120 (FIG. 16A) to extend the transfer arm into the pathof travel of the pickface 1150. As the pickface 1150 is carried by themultilevel vertical conveyor 150A in the direction of arrow 860 fingersof the bot the transfer arm (which may be substantially similar tofingers 1135 of the bot transfer station 140) pass through the fingers910 of the shelf 730 for transferring the pickface 1150 from the shelf730 to the carriage system 1135 (e.g. the pickface 1150 is lifted fromthe fingers 910 via relative movement of the shelf 730 and the bottransfer arm). As may be realized, the pitch P between shelves may beany suitable distance for allowing the transfer of pickfaces between themultilevel vertical conveyor and the bots 110 while the shelves 730 arecirculating around the multilevel vertical conveyor at a substantiallycontinuous rate. The bot transfer arm may be retracted (in a mannersubstantially similar to that shown in FIGS. 17C, 17D with respect tothe bot transfer station 140) so that the pickface 1150 is no longerlocated in the path of travel of the shelves 730 of the multilevelvertical conveyor 150A. It is noted that in alternate embodiments, wherethe bot transfer stations 140 are used, the positioning device 1140 maybe extended through the fingers 1135 and the carriage system 1130 (FIGS.17A-17D) may be moved in the direction of arrow 1180 for abutting thepickface 1150 against the positioning device 1140 effecting positioningof the pickface 1150 in a predetermined orientation relative to, forexample, the bot transfer station 140. The carriage system 1130 may befully retracted as shown in FIG. 17D for transfer of the pickface 1150to a bot 110.

Referring to FIGS. 16D and 18B, for transferring loads in the outbounddirection (e.g. moving pickfaces from or out of the storage andretrieval system) the bots 110 pick one or more pickface, such aspickface 1150, from a respective predetermined storage area of thestorage structure. The pickfaces may be extended into the path of theshelves 730 of the multilevel vertical conveyor 150B (which issubstantially similar to conveyor 150A) by the transfer arm of bot 110through an extension of the bot transfer arm relative to a frame of thebot 110. It is noted that the pickfaces, such as pickface 1150, may beplaced on the multilevel vertical conveyor 150 in a first predeterminedorder sequence. The first predetermined order may be any suitable order.The substantially continuous rate of movement of the shelves 730 in thedirection of arrow 870 cause the fingers 910 of the shelf 730 to passthrough the fingers of the bot transfer arm such that the movement ofthe shelf 730 effects lifting the pickface 1150 from the fingers of thebot transfer arm. The pickface 1150 travels around the multilevelvertical conveyor 150B to an out-feed transfer station 160 (which issubstantially similar to in-feed transfer station 170) where is itremoved from the shelf 730 by a conveyor mechanism 1030 in a mannersubstantially similar to that described above. The pickfaces may beremoved from the multilevel vertical conveyor 150B by, for example theout-feed transfer stations 160 in a second predetermined order sequencethat may be different and independent from the first predetermined ordersequence. The second predetermined order sequence may depend on anysuitable factors such as, for example, the store plan rules describedbelow.

It is noted that the respective transfer of pickfaces between themultilevel vertical conveyors 150A, 150B and the in-feed and out-feedtransfer stations 170, 160 may occur in a manner substantially similarto that described above with respect to the bots 110 and bot transferstations 140. In alternate embodiments transfer of pickfaces between themultilevel vertical conveyors 150A, 150B and the in-feed and out-feedtransfer stations 170, 160 may occur in any suitable manner.

It should be understood that the exemplary embodiments described hereinmay be used individually or in any suitable combination thereof. Itshould also be understood that the foregoing description is onlyillustrative of the embodiments. Various alternatives and modificationscan be devised by those skilled in the art without departing from theembodiments. Accordingly, the present embodiments are intended toembrace all such alternatives, modifications and variances that fallwithin the scope of the appended claims.

1. An autonomous transport vehicle for transferring case units to andfrom predefined storage areas of at least one elevated storage rack inan automated case unit storage system, the autonomous transport vehiclecomprising: a frame configured so that the autonomous transport vehicletraverses, as a unit, picking aisles and lanes interconnecting thepicking aisles that are alongside each of the at least one elevatedstorage rack for transferring case units between the predefined storageareas and a case unit input or output; and a controller connected to theframe, the controller being configured to effect movement of theautonomous transport vehicle on the picking aisles and lanes foraccessing each storage area of the at least one elevated storage rack;and an effector integral to and dependent from the frame, the effectordefining a case unit seating surface contacting the case unit being heldby the effector, the effector being configured to hold the case unitsand being configured to transfer the case units in a substantiallyvertical hand off exchange between the autonomous transport vehicle andeach storage area.
 2. The autonomous transport vehicle of claim 1,wherein the effector is configured to transfer the case units in asubstantially vertical hand off exchange between the autonomoustransport vehicle and at least one vertical lift.
 3. The autonomoustransport vehicle of claim 2, wherein the autonomous transport vehicleis configured to transfer case units between each storage area of the atleast one elevated storage rack and the at least one vertical lift withone pick.
 4. The autonomous transport vehicle of claim 2, wherein theautonomous transport vehicle is configured to transfer case units to apredetermined area of the storage area of the at least one elevatedstorage rack.
 5. The autonomous transport vehicle of claim 4, whereinthe effector of the autonomous transport vehicle is configured tointerface with at least one elongated finger of a support shelf of thestorage area for transferring the case units in a substantially verticalhand off exchange between the support shelf and the autonomous transfervehicle.
 6. The autonomous transport vehicle of claim 1, wherein theframe has a first end and a second end, the autonomous transport vehiclefurther includes a pair of individually operable drive wheels disposedat the first end and driven by a drive system and a pair of idler wheelsdisposed at the second end.
 7. The autonomous transport vehicle of claim1, wherein dynamic allocation of case units comprises the independentautonomous transport vehicle being configured to stop at a dynamicallydetermined position along the picking aisles for aligning at least aportion of the effector with the at least one case unit or empty spacelocated on the at least one elevated storage rack for effecting thesubstantially vertical hand off exchange of the at least one case unitbetween the autonomous transport vehicle and each storage area.
 8. Theautonomous transport vehicle of claim 1, wherein the autonomoustransport vehicle includes guiding devices with sensors for detectingraised support surfaces, separated by open channels, of slatted storageshelves of the predefined storage areas for effecting dynamic allocationof the case units in the predefined storage areas.
 9. The autonomoustransport vehicle of claim 8, wherein the effector of the autonomoustransport vehicle is configured to interface with the slatted storageshelves for transferring the case units in the substantially verticalhand off exchange between each support shelf and the autonomous transfervehicle.
 10. A method for transferring case units to and from predefinedstorage areas in an automated case unit storage system, the methodcomprising: providing a frame of an autonomous transport vehicle fortraversing, as a unit, picking aisles and lanes interconnecting thepicking aisles that are alongside each of at least one elevated storagerack of the automated case unit storage system for transferring caseunits between the predefined storage areas and a case unit input oroutput; and effecting movement of the autonomous transport vehicle, witha controller connected to the frame, on the picking aisles and lanes foraccessing each storage area of the at least one elevated storage rack;and transferring the case units in a substantially vertical hand offexchange between the autonomous transport vehicle and each storage areawith an effector integral to and dependent from the frame, the effectordefining a case unit seating surface contacting the case unit being heldby the effector.
 11. The method of claim 10, further comprisingtransferring the case units in a substantially vertical hand offexchange between the autonomous transport vehicle and at least onevertical lift with the effector.
 12. The method of claim 11, whereintransferring case units between each storage area of the at least oneelevated storage rack and the at least one vertical lift is effectedwith one pick.
 13. The method of claim 11, further comprisingtransferring case units with the autonomous transport vehicle topredetermined areas of the storage area of the at least one elevatedstorage rack.
 14. The method of claim 13, wherein transferring the caseunits to the predetermined areas of the support shelves includesinterfacing the effector of the autonomous transport vehicle with atleast one elongated finger of a support shelf of the storage area fortransferring the case units in a substantially vertical hand offexchange between each support shelf and the autonomous transfer vehicle.15. The method of claim 10, wherein the frame has a first end and asecond end, the autonomous transport vehicle further includes a pair ofindividually operable drive wheels disposed at the first end and drivenby a drive system and a pair of idler wheels disposed at the second end.16. The method of claim 10, wherein the dynamic allocation of case unitscomprises the independent autonomous transport vehicle stopping at adynamically determined position along the picking aisles for aligning atleast a portion of the effector with the at least one case unit or emptyspace located on the at least one elevated storage rack for effectingthe substantially vertical hand off exchange of the at least one caseunit between the autonomous transport vehicle and each storage area. 17.The method of claim 10, further comprising detecting, with guidingdevices of the autonomous transport vehicle where the guiding deviceshave sensors, raised support surfaces of slatted storage shelves of thepredefined storage areas, for effecting dynamic allocation of the caseunits in the predefined storage areas, wherein the raised supportsurfaces are separated by open channels.
 18. The method of claim 17,wherein the effector of the autonomous transport vehicle interfaces withthe slatted storage shelves for transferring the case units in thesubstantially vertical hand off exchange between each support shelf andthe autonomous transfer vehicle.